article is about Jawa forks and came about as I decided to replace the early
chrome bottomed forks on a 634 combo with later alloy bottomed forks from a
first lesson is to look after your forks by checking that there are no
splits in the rubber gaiters. Look
very carefully - both my “new” forks looked to have perfect gaiters when
in fact both were split. If
water enters the gaiters then you are in for big trouble as it will not
drain out. There will be rapid rusting
inside the gaiter (see picture below).
The stanchion is totally covered with wet
rust. Lesson 2 is to check the
black coating on the fork bottoms. You
can see from the picture (left) that when damaged, water gets behind the
black paint and the alloy oxidises to a white/grey powder.
It is possible to remove this and polish up the alloy but it is a
long job and will never look pretty or smooth unless powder coated.
Lesson 3 is to check that any steel bolts and
screws into the alloy do not seize. Remove
them periodically and after cleaning the thread refit with a coating of
copper based grease on the thread. If
the bolts seize then they are likely to break off, as has happened in the
lug nearest to us. Yes that
broken stud can be drilled out or spark eroded but it is another difficult
job needing an engineer or some serious DIY equipment. So, the fork leg shown in plate 1 was fit only for the scrap bin. I
managed to save just 2 parts – a plastic spacer and a metal breather plug.
One comment on my old forks – the fork nuts
still had the black plastic transit bungs in the breather holes which should
have been removed when the bike was prepared for the road in 1980.